Fiber impregnated reinforced catalyst carrier and a process for the production thereof

ABSTRACT

A fiber-impregnated reinforced catalyst carrier and a process for the production thereof, which process comprises mixing ceramic fibers to pulverulent alumina, moulding the mixture to the desired shape under addition of water and a suitable organic solvent, curing the moulded product for one hour so that the moisture may not be removed therefrom, and drying and calcining the moulded and cured product.

United States Patent [191 Kaneko et al.

[ Oct. 14, 1975 [54] FIBER IMPREGNATED REINFORCED CATALYST CARRIER AND APROCESS FOR THE PRODUCTION THEREOF [75] Inventors: Yasuhisa Kaneko;Fumiyoshi Noda,

both of Toyota, Japan [73] Assignee: Toyota Jidosha Kogyo KabushikiKaisha, Toyota, Japan 22 Filed: Apr. 30, 1973 21 Appl. No.: 355,429

[30] Foreign Application Priority Data May 4, 1972 Japan 47-44469 [52]US. Cl 252/455 R; 252/463; 423/212; 423/213 [51] Int. Cl. B01J 29/06;301] 23/08 [58] Field of Search 252/455 R, 463

[56] References Cited UNITED STATES PATENTS 3,125,539 3/1964 Teague252/455 R 3,288,615 11/1966 Btes et a1 252/455 R X 3,562,184 2/1971 Doddet al. 252/455 R Primary ExaminerPaul F. Shaver Attorney, Agent, orFirm-Stevens, Davis, Miller & Mosher 2 Claims, No Drawings FIBERIMPREGNATED REINFORCED CATALYST CARRIER AND A PROCESS FOR THE PRODUCTIONTHEREOF BACKGROUND OF THE INVENTION Ceramic material in the shape ofpills or pellets or in a monolithic structure is used as a carrier for acatalyst intended for cleaning the exhaust gas of automotive vehicles.The catalyst carrier of this type has a drawback in that it is readilyworn out and destroyed under vibrations with rapid reduction in thecleaning performance and thus can not be used for a prolonged time.

SUMMARY OF THE INVENTION The present invention relates to a carrier fora catalyst used for cleaning exhaust gas of automotive vehicles. Thecatalyst carrier according to the present invention is reinforced byceramic fibers dispersed therein, with a view in improving itsvibration-resistant properties.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to acatalyst carrier reinforced with ceramic fibers thus having a markedlyimproved resistance to vibration.

More particularly, various pulverulent ceramic material usedconventionally as catalyst material, such as alumina, mullite andcordierite, can be used as ceramic material.

On the other hand, the ceramic fibers of Al O -SiO or ZnO that do notlower the catalytic property of the catalyst, may be used as ceramicfibers that are added for the purpose of reinforcing the catalystmaterial.

Preferably, the ceramic fibers may be in the range of l to p. indiameter and about 1 to 3 mm in length, with consideration that thesefibers are subjected to the mixing and granulating steps, and thegranulated product must have sufficient strength. The quantity ofaddition of the ceramic fibers differs with the pulverulent ceramicmaterial and the ceramic fibers used and may preferably be in the orderof 2 to 5 percent.

The uniform mixture of the pulverulent ceramic material and the ceramicfibers may then be moulded, dried and calcined in the conventionalmanner for producing the fiber-reinforced catalyst carrier in granulatedform.

The advantages to be accrued from the present invention are such thatthe compaction density can be and the thus obtained product was mixedfor 10 hours in a powder mixer. The mixture was then granulated by apan-typed granulator. The granulating step was carried out in such a waythat the p-alumina powders added with the above mentioned ceramic fiberswere introduced gradually into a pan (Le. a flat saucer), which wasrevolved at 17 to 22 r.p.m., while water was sprinkled in a mist overthe mixture. This operation was carried out for 17 minutes and thepill-like p-alumina having the diameter of 3 to 6 mm and added withceramic fibers was obtained.

The thus obtained pill-like p-alumina added with the ceramic fibers wascharged into a vinyl bag and allowed to stand for 3 hours for curing.The pill-like material was then dried at 110C for 15 hours and thencalcined at 700C for 2 hours to obtain the catalyst carrier.

Table 3 shows the properties of the pill-like catalyst carried produced,from usual p-alumina powders not impregnated with the ceramic fibers, inthe same way as above, and those of the catalyst carrier produced inaccordance with the present Example. It is seen from this Table that thesurface area of the inventive product is somewhat reduced as compared tothe conventional one, but there is not much difference between the twoin respect of compression strength. The inventive product has thecompaction density smaller than that of the conventional one byapproximately 0.15g/cm The various properties of the two products weremeasured in the two kinds of calcined products having diameters of 3.0to 4.0 mm and 4.0 to 5.0 mm, respectively.

Table 1 Properties of p-alumina Table 2 Properties of ceramic fiberslowered without any marked reduction in the compresitem measured valuession resistance, that the catalyst layer can be speedily Al O 60 217heated to a temperature of catalytic activity owing to 6 the loweredcompaction density and that the breaking Ch I I Fe o 0.2%

emica strength and vibration resistance of the catalyst carrier ComposiO2 02% can be markedly improved. tion CaO 0.1% MgO 0.1% EXAMPLE 1 Nazo04% 2 percent of ceramic fibers, the propertles of which fiber diameter(average) 2-3 are tabulated in Table 2, were added to p-alumma powfiblength (avgrage) L8 mm ders, the properties of which are tabulated inTable l, SPECIFIC Weight 2/ Table 3 Various properties of the inventiveand conventional products bulk density compaction compression surfacesample diameter (10 ea average density strength area glcm (glcm(measured of (m /g) 30 samples) conven- No. l 3.0-4.0 1.79 0.80 9.3-l2.2218 tional Table 3 -Continued Various properties of the inventive andconventional productsv bulk density compaction compression surfacesample diameter ea average density strength area g/C (g/cm) (measured of(m /g) 30 samples) No. 2 4.0-5.0 1.80 0.78 9.l-l3.0 225 No. 3 3.0-4.01.66 0.60 22.7-12.4 190 inventive TEST EXAMPLE 1 To check for strengthof the material, a test piece in the form of a bar 10 X 10 X 30 mm wasprepared and checked for its breaking strength.

The above test piece was prepared in such a way that 2 percent ofceramic fibers (see Table 2) was added to p-alumina powders in the samemanner as in Example 1, the product thus obtained was mixed in a powdermixer for 10 hours, the resulting mixture was added with 10 wt. percentof water and agitated for 30 min- Table 4 Breaking strength itemconventional (kglcm sample 1 2 3 4 average conventional 4.1 2.5 3.8 4.33.7 inventive 7.2 8.6 9.3 8.8 8.5

It is seen from this Table 4 that the breaking strength of the inventiveproduct was markedly superior to that of the conventional one.

TEST EXAMPLE 2 A durability test was carried out on the inventivecatalyst carrier product No. 3 produced in accordance with Example 1 andthe conventional catalyst carrier product No. 1. The test conditionswere such that the catalyst carrier was packed within a catalyst mufflerand actually mounted on a vehicle. After running the vehicle 800 kmunder adverse road conditions, the sum of wear and destructionpercentages was checked.

Table 5 shows the results of the test.lt is seen from Table 5 that thedurability or vibration resistance of the inventive product is markedlysuperior to that of the conventional one.

Table 5 Test Result item the sum of wear and destruction sampleperccntageslpercents) conventional No. l 2L7 inventive No. 3 9.3

EXAMPLE 2 5 percent of ceramic fibers, the properties of which aretabulated in Table 7, was added to 'y-alumina powders, the properties ofwhich are tabulated in Table 6, and the thus obtained product was mixedfor 10 hours in a powder mixer as in Example 1. The mixture thusobtained was then granulated by a pan-type granulator. The granulatingprocedure was carried out in such a manner that the y-alumina powdersadded with the above-mentioned ceramic fibers were introduced graduallyinto a pan (i.e. a flat sauce pan), which was then revolved at 17 to 22r.p.m., while water was sprinkled in a mist over the mixture. Thisoperation was carried out for 20 minutes to obtain pill-like y-aluminahaving the diameter of 3.4 to 4.8 mm and added with the ceramic powders.The granulated product thus obtained was dried at 659C for 50 hours andcalcined at 800C for 2 hours for obtaining the fiber-impregnatedpill-like catalyst carrier.

Table 6 Various properties of y-alumina.

item measured values lg loss 5.0% Al O 94.7% chemical composi- Fe o0.03% tion SiO 0.07% Na O 0.20%

true specific density 3.0-3.3 surface area 250-350 m lg average particlesize l3 p.

Table 7 Various properties of ceramic fibers item measured values A1 4SiOz 5 Ffigog TiO CaO

MgO Na O B203 chemical composition Table 8 shows the properties of thepill-like catalyst carrier produced from the usual 'y-alumina powdersnot impregnated with ceramic fibers in the same manner as above andthose of the catalyst carrier produced in accordance with the presentExample. It is seen from this Table that the surface area of theinventive product is somewhat reduced as compared with the conventionalone, but there is not much difference between the two in respect tocompression strength. The inventive product has the compaction densitysmaller than that of the conventional one by approximately percent. Thevarious properties of the two products were measured of two kinds ofcalcined products of diameters 3.0 to 4.0 mm and 4.0 to 5.0 mm,respectively.

Table 8 It is seen from this Table 9, that the vibration resistance ofthe inventive article is markedly superior to that of the comparativeone.

EXAMPLE 3 3 percent of ceramic fibers, the properties of which aretabulated in Table 11, were added to cordierite powders, the propertiesof which are tabulated in Table 10, and the obtained product was mixedfor 10 hours in a powder mixer and thereafter the mixture was granulatedby a pan-type granulator in the same manner as in Example 1. Thegranulating step was carried out in such away that said cordieritepowders added with the above-mentioned fibers were gradually introducedinto a pan (i.e., flat saucer), which was revolved at 17 to 22 rpm,while 5 percent aqueous solution of polyvinyl alcohol was sprinkled in amist over said mixture. This operation was continued for 20 minutes togranulate cordierite pills having a diameter of 3.0 to 3.5 mm and addedwith ceramic fibers. Thereafter, this obtained pills were dried at 65Cfor 10 hours and then, calcined at 1250C for 3 hours thereby producingpill-like catalyst carriers impregnated with ceramic fibers.

Table 12 shows the properties of the pill-like catalyst carries whichwere produced, from conventional cordierite powders not impregnated withceramic fibers, in the same manner as above.

From the above Table, it is seen that the invented product decreases incompact density, while improving in compression strength in comparisonwith the conventional one.

Various properties of the inventive and conventional products bulkdensity compaction (g/cm, an density average of (g/cm") ten 1651 pieces)diameter (mm) item sample compression strength g an average of ten testpieces) surface area lg) No.5 No.6

conven tional No.7 No.8

inventive TEST EXAMPLE 3 A durability test'was carried out on theinventive product No. 7 and the conventional product No. 5. The

Table 9 Test result sum of wear and destruction percentages (percent)item sample conventional No. 5 23.3

inventive No. 7 8.7

Table 10 item properties MgO A1 0 SiO F8203 CaO Na O K 0 ChemicalComposition real density 2.53"/cm average particle size surface area l ml,

Table l 1 item properties more than Chemical 99% Composition Table ll-Continued rite powders not impregnated with ceramic fibers, in thesame manner as above.

From this Table, it is seen that the inventive catalyst item propertiesdiminishes in compact density, whtle improving 1n com- P pressionstrength. diameter 4-6 11. real density 5.9 "/cm surface area 1 m TESTEXAMPLE 5 fiber lcngth 2 mm The catalyst carriers produced according toExample Table 12 item diameter bulk density compaction compressionsurface (mm) (per 10) density strength area sample (glcm (g/cm) (per10),, m /g No.9 3.5-4.0 1.93 0.83 10.3-19.2 1 Conventional No.10 4.0-4.51.96 0.82 9.5-l6.3 1

No.11 3.5-4.0 1.77 0.72 12.3-20.5 1 invention No.12 4.0-4.5 1.83 0.77l4.5-22.3 1

TEST EXAMPLE 4 The catalyst carriers produced according to Example 3were filed within a catalyst muffler and actually mounted on a vehicle.After running the vehicle 1,000km under adverse road conditions, the sumof wear and destruction ratio was evaluated. The inventive product(1.7%) was much lower than a conventional one (8.8%).

4 were filled within a catalyst muffler and actually mounted on avehicle. After running the vehicle 1,000km under adverse roadconditions, the sum of wear and destruction ratio was evaluated. it isseen, from these results, that the inventive produce is 1.2 percent anda conventional one is 11.2 percent. Thus, the invented product is formore superior than a conventional one.

Table 13 EXAMPLE 4 3 percent of zirconium ceramic fibers, the propertiesitem properties of WlllCl'l are summarized in Table 11, were added tomurite powders, the properties of which are summa- 6 $3323: rized inTable 13, and the obtained product was mixed 6, 1 7, for 10 hours in apowder mixer and thereafter, the mix- 2 g-gig ture was granulated by apan-type granulator in the 2 02 same manner as in Example 1. Thegranulating step was N0 0 0.33%

3 carried out in such a manner that said murlte powders 23:25:33 g/madded with the above-mentioned ceramic fibers were ticle size 5gradually introduced into a flat saucer, which was re- Surface 1 volvedat 17 to 22 rpm, while 5 percent aqueous solu- 45 area Table 14 itemdiameter bulk density compaction compression surface (mm) (per 10)density strength area sample (g/cm 3 (g/cm" (per 10) m /g No.13 3.5-4.01.94 0.91 13.5-17.7 1 conventional No.14 4.0-4.5 1.97 0.87 l4.6-20.5 1

No.15 3.5 -4.0 1.88 0.82 16.3-20.5 1 invention tion of polyvinyl alcoholwas sprinkled in a misty form over the mixture. This operation wascontinued for 15 minutes to granulate murite pills having a diameter of2.5 to 3.3mm and impregnated with said ceramic fibers. Thereafter, theseobtained pills were dried at C for 10 hours and then calcined at 1360Cfor 3 hours thereby producing pill-like catalyst carriers impregnatedwith said ceramic fibers.

Table 14 shows the properties of the pill-like catalyst carriers whichwere produced, from conventional mu- What is claimed is:

1. A fiber-impregnated reinforced catalyst carrier characterized in thatceramic fibers of Al O SiO or ZrO having a diameter of l to 10p. and alength of l to 3 mm are dispersed in the ceramic catalyst carriermaterial in the amount of 2-5 weight percent.

' 2. The ceramic catalyst carrier of claim 1, wherein said ceramiccatalyst material is p-alumina, 'y-alumina,

cordierite or mullite.

1. A FIBRE-IMPREGNATED REINFORCED CATALYST CARRIER CHARACTERIZED IN THATCERAMIC FIBRES OF AL2O3-SIO2 OR ZRO2 HAVING A DIAMETER OF 1 TO 10 AND ALENGTH OF 1 TO 3 MM ARE DISPERSED IN THE CERAMIC CATALYST CARRIERMATERIAL IN THE AMOUNT OF 2-5 WEIGHT PERCENT.
 32. THE CERAMIC CATALYSTCARRIER OF CLAIM 1, WHEREIN SAID CERAMIC CATALYST MATERIAL IS P-ALUMINA,Y-ALUMINA, CORDIERITE OR MULLITE.